Electrical testing-circuits



C. S. DEMAREST. ELECTRICAL TESTING CIRCUITS.

I APPLICATION FILED NOV. 6, I919- Patented Dec. 6, 1921..

I N V EN TOR. 63 JIfiem/wl I ATTORNEY c. s. DEMAREST. ELECTRICAL TESTING CIRCUITS.

APPLICATION FILED NOV- 6, I919- 1,399,695u

2 SHEETS-SHEET 2.

IN V EN TOR.

BY W

ATTORNEY Patented Dec. 6, 1921.

UNITED smrss PATENT OFFICE.

CHARLES S. DEMAREST, OF YORK, N. Y., ASSIGNCR 110 AMERICAN TELEPHONE AND TELEGEAIEI-I COMBANY, A CORPORATION OF NEW YORK.

iseaees.

Specification of Letters Patent.

ELECTRICAL TE TING-CIECUIT$.

Patented Dec. 6, 1921.

Application filed November 6, 1919. Serial No. 335,990.

To all to have it may con cern Be it known that l, Unsnnns ELDEMAR- nsr, residing at New York, in the county of New York and State of New York, haveinvented certain improvements in Electrical Tlcsting-Circuits, of which the following is a specification.

This invention relates to electrical testing circuits and more particularly to a circuit adapted for testing telegraph circuits superimposed upon long distance telephone lines.

Testing circuits in use hitherto for testing the condition of telegraph circuits superimposed on telephone lines, comprise what is commonly known as a test circuit and also one or more Morse test circuits. 'llhe so-ca-lled test circuit is adapted to make the ordinary tes s for circuit trouble such as, for instance, those to determine the presence oi? an open circuit, a short circuit or a ground upon the lineunder test, or todetermine the polarity and thevoltage of the Morse battery associated with the 11116 under test. This circuit is equipped with a plurality. of batteries of suitable potentials, switching means for applying potentials of opposite polarities to the line under test and a combination voltmeter and ainmeter for measuring the potentials and currents in the said circuit. The test circnit has also connected with it an operators telephone set, in order to render it practicable to n'iaintain telephone conversation either over the line under test or over a trunk or subscrihers line extending from the testing o'lhce. The Morse test sets cornprise Morse telegraph equipment having sources of direct current associated therewith, whereby potentials ott opposite polarities may be applied to the lines and switching means for connecting the ammeter winding of the said voltmeter-a1n1neter with. the said telegraph circuit, in order thatthe (various pieces of apparatus may beadjusted for the proper current flow.

l lxperience has, shown that the arrangeicnt just described is too inflexible, in that certain parts of the circuit are so related as to prevent theirseparate use simultaneously. For example, the telephone set is connected with the test circuit in such manner that teleiiihone conversation cannot be carried on while tests arebeing made with the other apparatus associated with the said circuit. It is desirable sometimes to carry on a telephone conversation over one line circuit while tests are being made over another line circuit and accordingly one of the objects of this invention is to provide switdiing means whereby the telephone equipment may be connected either with separate cords, thereby forming a telephone circuit separate and distinct from the test circuit, or the said equipment may beconnected directly with the test circuit.

Another object of this invention is to provide a special cord circuit for connect:

ing the amineter winding of the combination voltmeter-ammeter with a line under test, the said cord circuit being separate and distinct from the test circuit heretofore referred to, and to provide switching means which will render it impossible to connect the voltmeter winding with this test circuit at the same time that the ammeter winding is connected with either the special cord circuit or with the Morse test circuits.

Other objects of this invention will appear from the following description when read in connection with the drawing, Fig

ure 1 of which shows a transmission line adapted for joint telephone and telegraph use and also a ringdown telephone trunk line, and Fig. 2 shows the testing arrangement comprising a test circuit, a telephone circuit, two Morse test circuits, and the special ammeter cord circuit.

In Fig. 1 L represents a transmission line adapted for joint telephone and telegraph use, terminating at a toll test board in the the acks jacks J and looped to contacts of J :Aesociated therewith is the composite apparatus X, and the composite ringer KR, both of which may be of any well known type. The telephone circuit terminates at a telephone switchboard in the jack J which is adapted to cooperate with. the plug P of a toll cord circuit located at the said switchboard. The telegraph branches 1 and 2 extend from the composite apparatus X, to the Morse terminals MT, and MT respectively, which are located at the Morse board. The terminal MT has associated therewith a plurality of jacks, J J and J,, by means of which a plurality of Morse subscriber lines represented by the line MS may be connected with the Morse line. The jack J, of this terminal is known as the loopcuits shown in Fig. 1.

and plugs associated .si de. alone,

circuit which terminates at the Morse board in jacks J and J The pairs of conductors 3, 4, 5, 6 and 7 extend from the cord terminals of the Morse board to the circuit arrangementshown in Fig. 2 which is located at the Morse board. Each of these pairs of conductors terminates in three separate cords, each cord terminating in a separate plug, which is of the two-conductor type,

having tip and sleeve contacts only. One of the said cords is connected with the tip side of the line, another is connected with the ring side of the hne and the lilllll lS (30l1- l l nectetl with ooth the tip and ring SlllOS ol- Salt line. Thus, for example, the tip side of pair 3 is connected with cord 10, which terminates in plug P The ring side of the said pair is connected with cord 11, which terminatesin plug P and both sides of the said pair are connected with cord 12, which terminates in the plug P Each of the remaining pairs, 4, 5, 6 and '7, are terminated in three-cords each cord having a' separate plug By means of the plurality of cords with each connecting pair, either the tip side alone or the ring or both sides together, may be connected with the testing arrangenent shown in Figure 2.

n Fig. 2, we have 'in'reality five separate circuits which,"taken in combination, constitute the arrangement for testing the cir- Thcse circuits are represented by the letters A, B, O, D and E.

represents the so-cal'ledtcst circuit which may broadly be understood as extending from the plugs associated with pair i to key IQ. represents a telephone circuit which extends from the plugs associated with pair 3 to the telephone transmitter and receiver shown to the right of the drawing.

C and D represent Morse test circuits, each having Morse telegraph .iequipmcnt asso adapted to have the ammeter winding of the voltmeter-animeter A, connected therein by operation of thc keys K and K respectively. E represents the amn eter test circuit which extends from the plugs associated with the cord to the ammeter winding of the combination. instrument. Thetest circuit A. comprises a key K which when moved to the right connects the telephone apparatus of the circuit B with the test circuit A and when moved to the left connects the voltmeter winding of the combination instrument with the circuit A. Themovement or this key to the left also disconnects the ammeter winding of the said instrument from the ammetcr test circuit it and short circuits the latter circuit. Associated with the circuit A. are the Morse butteries B, and 13,, which are poled oppositely and are adapted to be connected with the test circuit by the key K The key K is adapted, when thrown to the right, to open the tip side of the line and to ground the ring side in series with the voltmeter. The movement of this key to the left opens the ring side of the circuit and grounds the tip side in series with the volt-meter. Key K when moved to the right, reverses the connection of the conductors l3 and id with the sides of pair 4. The movement of this key to the left elicit-circuits the two sides of pair i.

The telephone circuit ll comprises an opcrtors haul set ll which is lititlllllhl to he connected by the insertion oi the plugs l.,,

in the jacks J The key K when moved to the right, connects the receiver oi. the telephone set across the circuit in a monitoring relation. The movement of the key to the left connects the set with the circuit in a talking relation. The key K when moved to the right, applies ringing current to the line and when moved to the left connects a battery 13;, across the circuit, in order to provide talking currentfor an instrument such as a lineman s test set, which may be connected across the distant end of the telephone line with which the telephone circuit might be connected.

The Morse test circuit C comprises h'lorsc key K a relay R, and a sounder 8,. The

key K is adapted normally to connect battcry of positive polarity with the line, but by moving the key to the right the polarity may be changed. The movement of the key to the left disconnects the local battery from the line and grounds the line circuit. The key K when moved to the right, connects the local Morse testing equipment with the drop side of the Morse terminal circuit and when moved to the left, the line side of the circuit. The movement of the key K connects the ammeter winding of the combination instrument in series with the Morse testing equipment. In a similar manner the various corresponding pieces of ai'iparatus associated with the circuit D perform the same functions as those in the circuit (7.

The circuit E, which may he termed the ammetcr tcst circuit, may he considered as extending from the plugs associated with the pair 7 through the contacts of keys K K and K, to the ammeter lit) cuit the said conductors.

incense combination instrument. It has been noted that the key K when operated toward the left-disconnects the arnmeterwinding oi the combination circuit from the conductors that normally serve to connect it with the circuits C, D and. E. When key K, is normal the operation otthe key K will serve to connect the amineter with the (circuit C and disconnect it from the conductors hetweenkey K and key K and short cir- Furthermore, When keys IQ and K are in their normal positions, the operation ot key K will connect the ainmeter witlrthe circuit I) and disconnect it troin the circuitfllll and short circuit the conductors of circuit The nature of the inventionJwillhe more fully understood from the following description of the manner in which the various circuits operate:

In the operation of the test circuit A, it it isdesired, for example, to measure the potential across the Morse line and drop, the

blilg P ot' the loopingkcord is inserted. in

xthelooping jack J G otthe Morse terminal hfll and the key K is moved toward the i the battery jack J left. This connects the voltmeter winding; across the line and drop and indicates approximately the total voltage acting in the It key K is moved to the right scrihedythe tip le ot' the circuit is opened. and thering;- side connected to ground. The voltmeterwill' then indicate approximately the potential; of the battery connected with of: the Morse terminal M l and the direction of the deflection will indicate the polarity. It keys K andlt are both operated to the left and plug P remains connected with the jack the rin side of the testin circuit is ooened l": t1

and the tip side will be grounded through the voltlneterr The voltmeter will then in dicate thepotcntial and the polarity of the battery connected with the distant end of the linen The batteries ll'l and are adapted for use in making; voltmeter tesu; tor continuity, crosses, or grounds upon the Morse circuit. These tests, which are made in the well knownmanner, may be effected by the operation of the various keys associated with the test circuit A.

The mode of operation of the telephone circuit B is astollows:

The plug P which is associated with. the tip side oi the telephone circuit, is iserted in jack J and the plug P which is associated with the ring side oil the telephone circuit is insertedinthe jack J As a result, the ringdown telephone trunk circuit LA is connected with the telephone circuit of the testing arrangement shown in Fig. 2. ll: it desired totalk over this line, the key K is operated tothe leit, thereby connecting the telephone equipment with the line. lit

it is desired to listen on the circuit, the key hi is moved to the right, thereby disconnecting the receiver from the telephone set and connecting it directly to the circuit in series with the condensers. It in the process of talking it is desired to supply bat-teryto the instrument connected with the distant end oi the line, the key hi is operated toward the left, thereby bridging; the battery l1 across the telephone circuit. The telephone circuit loops through the right hand contacts of: key K in such a manner as to be normally discoi'inected from the test circuit it, but adapted to he connected thereto by the operation in a right hand direction of the key li lit will be seen, therefore, that by means oi the switching arrangement the telephone circuit B may be used to carry on. a telephone conversation. over the line L for example, at the same time that the circuit A is being used to make various circuit tests upon the telegraph circuit connected with the Morse terminal. liil'l i If the plugs P and P of the test cords had been connected with the jacks J and J of the line L in order to make circuit tests upon the line "L mission solely, then the telephone set associated with the circuitlll might be connected with the test circuit A by moving the key .114 to the right and used in connection with The arrangement shown in h A rovides means for combining the test circuit ii an d the telephone circuit B, when conditions render such use desirable or necessary, and for rendering them separate and distinct circuits in order to provide for carrying on telephone conversation over one circuit when tests are being made over a diftorent circuit.

he mode of operation of the Morse test circuits U and l) being substantially the same. ahscription ot one will therefore ly to the other. It the plug P of the ping cord ot the Morse test circuit C is inserted in the looping jack J of the Morse tr urinal llil'l and all keys of the test circuit are normal, the hlorse relay and key will be connected in series with the circuit associated with the ilx'lorse terminal hil and signals may thus be transmitted from the test cord to the various lifloij'se stations connected with the line. lit it is desired to determine the 1(]i.,l'11llllll oi the current in the telegraph circuits or to adjust the hi; .rse battery taps or the duplex sets to the proper value the annneter winding of the combination instrrunent Vik may be connected in the circuit by the operation of the key K This connects the ammeter winding: in series with the circuit C and the line and drops circuits oil the Mouse terminal llil'l in a similar manner the ammeter winding: in I no connected with the circuit D by the operation of the key K but the a1ndesigned for telephone trans-i the resistance in the test circuit A,

certain adjustments, this single cords, with which K and K olthe testing nation voltmeter-ammeter meter circuit is so arranged that should keys phone circuit adapted for connection with K, and K be operated simultaneously, the ammeter will be connected with circuit C and no interference between the circuits G and D will result therefrom. Furthermore, if key K should be operated to the left in order to connect the voltmeter winding with the conductors of the ammeter test circuit will be short-circuited and the voltmeter winding will be connected to the testv cords. This, therefore, avoids interference betweenrMorse circuits when the Morse test sets and the'test circuit A are being used simultaneously for testing different line circuits.

If it is desired to determine the magnitude ofthecurrent in a circuit, in order to make may be done by The pair 7 of this looping cord and are associated the plugs P P and P If, for example, the looping plug P is inserted in the jack J, of the Morse terminal MT and keys K arrangement are in positions, the ammeter windmeans of the circuit E. circuit terminates in a their normal .ing of the voltmeter-ammeter will be connected in series with the Morse circuit connectedwith the-terminal MT In this manner adjustments of apparatus for the desired current flow may be readily made by means of this simple circuit, while the other morecomplex circuits are being used to make the tests for which they are specially adapted. A relay R is inserted in the circuit of the ammeter winding of the combiin order to protect the instrument against excessive currents.) This relay is designed to operate at a definite current value within the limit of the safe 'carrylng capacity of the ammeter wlnding. As soon as the relay operates, the

winding is short-circuited through the armature of the relay when operated, and the ammeter winding is thus protected. It will be apparent, therefore, that this invention provides' means for facilitating the connection of a single composite instrument with a plurality of circuits, which means are like wise adapted to prevent the simultaneous connection of the said instrument with any "two of a pluralityot test circuits.

Although this invention has been shown f embodied in a particular form or circuit arrangem ent,

it is apparent that it is not limited to such form or arrangement, but

' is capable of embodiment in other forms and arrangements, without departing from the g That is claimed is:

1. In a testing system, the combination of atest circuit adapted for connection with an electrical transmission line and having a measuring instrument associated therewith but normally disconnected therefrom, a tele- Iriorse a second electrical transmission line and switching means for connecting either said telephone circuit or said measuring instrument with said test circuit.

2. In a testing system, the combination of a test circuit adapted to measure the voltage of a transmission line, a telephone circuit, asecond test circuit adapted to test lines, a combination voltmeter and ammeter adapted for connection with said first and said second test circuits, means for combining said telephone circuit with said first test circuit and means for connecting the ammeter winding of said instrument with said second test circuit.

3. In a testing system, the combination of a voltage test circuit, a current test circuit, a Morse test circuit, a combination electrical measuring instrument adapted to indicate voltage and current values, switching means for connecting the voltage winding of said instrument with said. voltage test circuit and to short-circuit said current test circuit, and switching means associated with said Morse test circuit to connect the ammeter winding of said instrument with the said Morse circuit when said first switching means is normal and to short-circuit said current test circuit.

In testing system, the combination of a measuring instrument, a test circuit normally connected thereto, a plurality of test circuits normally disconnected from said instrument, switching means associated with h of said plurality of test circuits for connecting said instrument thereto and adapted to short-circuit the conductors of the test circuit normally connected with said instrument.

5. In a testing system, the combination of a test circuit adapted for connection with a transmission line, a second test circuit adapted also for connection with a transmission line, an electrical measuring instrument adapted to show voltage and current values, said measuring means being normally con- .nected with said second test circuit and s itching means associated with said first mentioned test circuit for voltage winding of said instrument thereto, said switching means being adapted to disconnect said instrument from said second test circuit and to short-circuitthe conductors of said second test circuit.

6. In a testing system, the combination of a plurality of test circuits, a meter, a signaling circuit, a plurality of line circuits, and means to disconnect the said meter from one of said test circuits and to connect said test circuit with said signaling circuit.

In testimony whereof, I have signed my name to this specification this 5th day of November, 1919.

CHARLES S. DEMAREST. 

